.left {
  width: 300px;
  height: 100vh;
  position: fixed;
  left: 0;
  top: 0;
  background: #3f3f3f;
}
.left img {
  width: 80%;
  display: block;
  margin: 50px auto;
}
.left li a {
  display: block;
  font-size: 16px;
  color: #fff;
  line-height: 60px;
  padding-left: 30px;
  border-bottom: 1px solid #2b2b2b;
  cursor: pointer;
}
.left li span {
  margin-right: 20px;
}
.left li a.active,
.left li a:hover {
  background: #2b2b2b;
}

.right {
  min-height: 100vh;
  background: #e0e3e8;
  box-sizing: border-box;
  padding: 40px 20px;
  margin-left: 300px;
}
